Indium-rich NMOS transistor channels

Abstract

Techniques are disclosed for forming high mobility NMOS fin-based transistors having an indium-rich channel region electrically isolated from the sub-fin by an aluminum-containing layer. The aluminum aluminum-containing layer may be provisioned within an indium-containing layer that includes the indium-rich channel region, or may be provisioned between the indium-containing layer and the sub-fin. The indium concentration of the indium-containing layer may be graded from an indium-poor concentration near the aluminum-containing barrier layer to an indium-rich concentration at the indium-rich channel layer. The indium-rich channel layer is at or otherwise proximate to the top of the fin, according to some example embodiments. The grading can be intentional and/or due to the effect of reorganization of atoms at the interface of indium-rich channel layer and the aluminum-containing barrier layer. Numerous variations and embodiments will be appreciated in light of this disclosure.

What is claimed is: 
     
       1. An integrated circuit comprising:
 a substrate; and 
 a fin extending from the substrate, the fin including
 a sub-fin layer including one or more group III-V materials, wherein at least a section of the sub-fin layer is laterally between portions of the substrate, 
 a first layer above the sub-fin layer, the first layer including indium and gallium, and 
 a second layer between the sub-fin layer and the first layer, the second layer including aluminum, 
 wherein the gallium concentration of the first layer is graded from a high concentration near the second layer to a relatively lower concentration at a top of the fin. 
 
 
     
     
       2. The integrated circuit of  claim 1 , wherein the indium concentration of the first layer is graded from a low concentration near the second layer to a relatively higher concentration at the top of the fin. 
     
     
       3. The integrated circuit of  claim 1 , wherein the indium concentration at the top of the fin is greater than the gallium concentration at the top of the fin. 
     
     
       4. The integrated circuit of  claim 1 , wherein the fin further includes a third layer between the sub-fin layer and the second layer, the third layer including indium and gallium. 
     
     
       5. The integrated circuit of  claim 4 , wherein one or both of the first layer and the third layer includes arsenic. 
     
     
       6. The integrated circuit of  claim 4 , wherein the indium concentration of the third layer is graded from a low concentration near the sub-fin layer to a relatively higher concentration near the second layer. 
     
     
       7. The integrated circuit of  claim 1 , wherein the at least a section of the sub-fin layer that is laterally between portions of the substrate is a first section of the sub-fin layer, the integrated circuit further comprising:
 insulator material above and in contact with the substrate, wherein at least a second section of the sub-fin layer is laterally between portions of the insulator material; and 
 a gate structure, wherein at least a portion of the first layer is laterally between portions of the gate structure. 
 
     
     
       8. The integrated circuit of  claim 7 , wherein at least a portion of the second layer is laterally between portions of the insulator material. 
     
     
       9. The integrated circuit of  claim 7 , wherein the second layer is above the insulator material, such that no portion of the second layer is laterally between portions of the insulator material. 
     
     
       10. The integrated circuit of  claim 1 , wherein the one or more group III-V materials included in the sub-fin layer comprises gallium and arsenic. 
     
     
       11. The integrated circuit of  claim 1 , wherein the second layer is in direct contact with the sub-fin layer, and the first layer is in direct contact with the second layer. 
     
     
       12. The integrated circuit of  claim 1 , wherein the aluminum concentration of the second layer and the indium concentration of the first layer are within 10% of each other. 
     
     
       13. An integrated circuit comprising:
 a fin including
 a first portion including one or more group III-V materials, wherein a bottom surface of the first portion is faceted; 
 a second portion above the first portion, the second portion including indium; 
 a third portion between the first portion and the second portion, the third portion including aluminum; and 
 a fourth portion between the first portion and the third portion, the fourth portion including indium; 
 
 a gate structure on top and side surfaces of at least a section of the fin; and 
 first and second insulator structures, 
 wherein at least a section of the fourth portion is laterally between the first and second insulator structures, and not laterally between portions of the gate structure. 
 
     
     
       14. The integrated circuit of  claim 13 , wherein each of the first and fourth portions include gallium and arsenic. 
     
     
       15. The integrated circuit of  claim 13 , further comprising:
 a substrate; and 
 insulator structures above and in contact with the substrate, wherein a first section of the first portion is laterally between two of the insulator structures, and a second section of the first portion is laterally between portions of the substrate. 
 
     
     
       16. The integrated circuit of  claim 13 , wherein:
 the gate structure is on top and side surfaces of the second portion of the fin, and on side surfaces of the third portion of the fin, such that both the second and third portions are laterally between portions of the gate structure; and 
 at least another section of the fourth portion is laterally between portions of the gate structure, and not laterally between the first and second insulator structures. 
 
     
     
       17. The integrated circuit of  claim 13 , further comprising:
 a source or drain region laterally adjacent to the second portion of the fin. 
 
     
     
       18. An integrated circuit comprising:
 a substrate; 
 insulator structures above and in contact with the substrate; 
 a multi-layer structure including
 a first layer including one or more group III-V materials, wherein a first section of the first layer is laterally between portions of the substrate, and wherein a second section of the first layer is laterally between two of the insulator structures, 
 a second layer including aluminum, the second layer above the first layer, and 
 a third layer including indium, the third layer above the second layer; 
 
 a gate stack at least on top and side surfaces of the third layer of the multi-layer structure; and 
 a source region and a drain region to respective sides of the third layer. 
 
     
     
       19. The integrated circuit of  claim 18 , wherein the aluminum concentration of the second layer and the indium concentration of the first layer are within 10% of each other. 
     
     
       20. The integrated circuit of  claim 18 , wherein the multi-layer structure further includes a fourth layer including indium, the fourth layer between the first layer and the second layer.